Trailer coupling



AUS- 2, 1938. cz.A R. `HENNICKE 2,125,611

TRAILER COUPLING Filed Sept. 26, 1936 2 Sheets-Sheet l 5 4 25 '2mal-goATTO EYS.

Allg. 2, 1938. x C, R, l||ENN|CKE V A 2,125,611

TRAILER. GOUPLING Filed Sept. 26, 1936 2 Sheets-Sheet 2 INVENTOR.

ATTORNEY,

Patented `Aug; 2, 1938 UNITED. STATES TRAILER OOUP'LING can a. nemiche,cinema nennt, ohio, a-

signor to The Eastern Malleable Iron Company, Naugatuck, Conn., acorporation of Connecticut `Application September 28, 1936, Serial No.102,643 sommi. (ol. eso-sais) This invention relates, as indicated, tocouplings for trailers, but has reference more particularly to acoupling 'of this character which is especially i adapted for use inconnection with the'towing of. house trailers by passenger automobiles,al-

` matically taken up or compensated.

To the accomplishment of the foregoing and related ends, said invention,then, l consists of the means hereinafter fully described andparticularly pointed out in the claims; the annexed drawings and thefollowing description setting forth in detail certain mechanismembodying the invention,

such disclosed means constituting, however, but one of variousmechanical forms in which the principle of the invention may be used.

In said annexed drawings;-

Fig. 1 is a view partly in plan and partly in section of the novelcoupling; i

Fig. 2 is a longitudinal cross-sectional view. taken on the line 2-2 ofFig. 1, and showing the couplinglocking and unlocking lever in partiallyunlocked position;

Fig. 3 is a fragmentary horizontal cross-sectional view, taken on theline 3--3 of Fig. 2;

Fig. 4 is a transverse vertical cross-sectional view, taken on the line4-4 of Fig. 1;

Fig. 5 is a transverse vertical cross-sectional view, taken on the lineapproximately indicated by the line 5-5 of Fig.,1;

Fig. 6 is a transverse cross-sectional view, taken on the lines 6-6inFigs. 1 and 2;

Fig. 7 is a view similar to Fig. 2, but showing the locking andunlocking lever in fully locked position; and

Fig. 8 is a view similar to Fig. 2, but showing the locking andunlocking lever in fully unlocked position.

Referring more particularly to the drawings. it will be seen that thecoupling comprises a drawbar l, the front portion 2 of which is shapedto provide a housing for the coupling elements to be described, and theear portion of which comprises diverging arms 3, whereby the drawbar isadapted to be rigidly secured to a trailer (not shown) l Depending fromapoint intermediate the diverging arms l is a tubular member 4 which isremovably secured to the drawbar and which provides a housing forajackscrew 5, on the lower end of which is mounted a caster wheel 6.This tubular member, jackscrew and caster form the elements of aconventional type of screw lift, which is no part of the presentinvention- It need only be mentioned here that the caster wheel isutilized to support the front end of the trailer when uncoupled from thetowing car and is adapted to be raised or lowered with the jackscrew bymeans of a detachable crank.

The housing 2 has downwardly extending parallel sides 1 and is closed atits front end by a wall il. The inner surface 9 of this end wall isshaped to conform to and provide a seat for the spherical surface of aball i0. which forms the tractor or towing-car element of the coupling.'Ihe ball i0 is mounted on a stud Il, the lower end of which is threadedso that it may be secured to the tractor or towing-car by means of thenut l2;

The ball is adapted to be maintained against the seat 9 by means of apressure block i3, which is pivotally mounted on a pin 'I4 secured inthe sides 1 of housing 2. The front surface I5 of this block is shapedto .conform to and provide a seat for the spherical surface of the rearportion of the ball I0. The block normally hangs in a substantiallyvertical position, as shown in Figs. 2 and 7, and when in such position,it will be noted that the spherical surface of the ball is substantiallyentirely enclosed by the surfaces 9 and i5.

The block i3 is provided with a downwardly andrearwardly extendingiinger I6, adapted to be engaged for the purpose of swinging the blockabout its pivot pin as will be presently described. The finger |6`isprovided on its lower surface with a shoulder or recess Il, and adjacentthisshoulder is an indentation or notch I1'. The

,block is further provided with an abutment I8 2| mounted inthe sides 'Iof the housing 2. 'Ihis lever comprises a bottom wall or base 22 havinga rounded edge 23 at the front, which is'curved to conform with thecurvature of the shoulder or recess I1 in the ilnger i3 of the block i3,and laterally spaced upstanding side, walls 2l, the front edges 2i ofwhich are arcuately curved to engage the arcuately curved surface I3 ofthe pressure block. The surface il and the front edges 2l are ofslightly.diiferent arcuate curvature for a purpose which will bepresently described.

The lever is further provided with an integral offset rearward extension23 forming a handle whereby the lever may be rocked about its pivot pin,and with a second laterally disposed extension 21 adapted to engage astop 23 on one of the walls 1 whereby to prevent downward movement ofthe lever beyond the locking position thereof, as shown in Fig. '1.

For the purpose of biasing the lever 20 to the pressure-block lockingposition shown in Fig. 7. and maintaining the same in such position, acoil spring 20 is provided which is interposed between 'the undersurface ofhousing 2 and a seat 33 which is pivoted, as by a pin 3l, tothe lever 23; at a point intermediate the pin 2l and the edge 23 of thelever. A

Having thus described the construction of the coupling, the operation,use. and advantages of the same will now be described.

It will be assumed that the caster wheel 3 is in trailer supportingposition and that the trailer coupling parts are as shown in Fig. 8,that is, ready for the trailer to be coupled to the towing car. Theparts are brought to this position by rotating the lever 2li in aclockwise direction. In the course of such rotation of the lever, thefinger I6 oi' the block i3 is engaged by the lever, thereby rotating theblock in a counter-clockwise direction. This movement is continued untilthe parts are in the position shown in Fig. 8, the spring 29 at thistime being fully compressed. The lever is then released, and the partswill remain in the position shown in Fig. 8, that is, the shoulder orrecess i1 of the pressure block will be in engagement with the edges 23of the lever. Due to the seating of the edge 23 in the recess orshoulder I1, and the fact that the sum of the distances from this seatto the axes of pins I4 and 2i is greater than the' distance betweenthese axes, the parts will be locked in the position shown. With` theblock and lever thus locked, neither can fall into the position shown inFig. 7, until the pressure block has been rotated sum-.- ciently tocause the shoulder i1 to clear the edge 23.

In order to couple the trailer with the towing car, the towing car isbacked to such a position that the ball iii is approximately under thepivot pin Il. The front end of the trailer is then lowered bymanipulation of the screw jack, and as the ball I3 strikes the abutmentil, or some other portion of the surface Il of the pressure block, thelatter is rotated suillciently to cause the shoulder I1 to move upwardlyso as to clear the edges 23 of the lever. 'Ihis unlocks the lever andpermits it to snap downward as a result of the expansion of spring 23,the edges 23 initially moving into the notch I1', which, as shown, issufficiently deep to freely receive these edges. In the course of thefurther downward movement of. the lever 20, the arcuately curved edges2l of the latter engage the arcuate surface I3- at the rear of thepressure block, and the wedging be stated that as wear of the ballsurface or surfaces 3 and il occurs,the natural downward pressure of thespring 23 forces the lever 20 into a new position and automaticallytakes up this wear. 'I'his take-up movement is, of course, limited, andthe position of the lever shown in Fig. 7 is the ,extreme position,beyond which no further take-up can be accomplished. Movement of thelever below this position is, of course, prevented by the engagement ofthe extension 21 with stop 23. After the coupling has been effected, thecaster wheel 3 is elevated from the ground to an inoperative position',and the entire screw lift removed from the drawbar.

In lowering the trailer onto the ball lil, should the ball fail toengage the pressure block I3 and release it, coupling would neverthelessbe effected, as the instant the towing car and trailer are in motion.the natural back and forth play would result in sumcient movement of theparts to trip the pressure block and permit it to move to theball-locking position. Succeeding movements of the towing car andtrailer would-result in the lever 23 working down to the position shownin Fig. 7, so that no danger would exist in the possibility of a poorconnection. By incorporating the abutment I3 in the design of thepressure block, however, it is unlikely that the coupling and ball couldever be brought together without securing a tripping action which wouldrelease the pressure block. The coupling action, aside fromthe loweringof the trailer onto the ball, may therefore be considered as virtuallyautomatic in character.

It may be further noted that the axis of pivot pin 2| is in a planebelow the horizontal plane passing through the center of the ball III,so that in the eventv that the spring 29 should break or in any waybecome inoperative, the natural tendency of the lever would be to assumethe position shown in Fig. '1, and any likelihood or danger of thecoupler working open and permitting the trailer to uncouple itself wouldbe extremely remote. Furthermore, due to the fact that the bulk of thelever 2li is below a plane passing through the center of the ball andthe axis of pivot pin 2i, the strains imposed by sudden stops or backingup are transmitted by the bali through the pressure block and tothelever 20 in a direction which tends to lock the coupling rather than tounlock it.

In uncoupling the trailer, the jack screw is manipulated to cause thewheel 6 to engage the ground and to take the weight of the front end ofthe trailer off the ball lil on the towing car. The handle 23 is thenpulled downward'until the pressure block and lever are locked in theposition shown in Fig. 8, Upon further operation of the jack screw, thedrawbar is lifted clear of the bail, the caster wheel 6 assisting inthus lifting the drawbar because it permits the trailer to creep forwardsuillciently to cause the lower portion of the spherical surface 9 toclear the ball.

'Ihe use and design of the pressure block i3 are of extreme importance.The coupling could be made without utilizing such a pressure block bythe simple expedient of shaping the forward end of the lever 20 topartially encompass the spherical surface of the ball I0. In order tosecure an upward swing of i such a lever, the spherical surface of thefront end thereof could obviously not extend below a horizontal planepassing through the center of the ball, but the surface thus provided asa seat for the ball would result in a practical connection. Thedisadvantages of such an expedient, however, would be that it reducesthe amount of wearing surface, thereby shortening the life of theconnection and places a great deal more importance on the spring, inthat failure of the spring would result in the coupler automaticallyopening. In the present construction, on the other hand, through the useof the pressure block, a substantially full spherical seat for the ballis provided, and, as previously stated, the necessity for the block tobe swung upwardly before uncoupling makes accidental opening of thecoupling virtually impossible.

Finally, it may be noted that the forward portion of the spherical seatfor the wall is an integral part of the housing or drawbar. This makesfor safety, as it eliminates the use of a separate piece for this seat,which might become loosened and possibly fall off, permitting thetrailer to become uncoupled.

It is thus seen that a coupling has been provided which is as nearlyautomatic in operation and foolproof as is possible, the only attentionrequired consisting in unlocking the pressure block lever. Onceunlocked, however, the parts are maintained in unlocked condition, sothat recoupling requires no additional operation.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the mechanismherein disclosed, provided the means stated by any of the followingclaims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as myinvention:-

1. In a coupling for trailers, a ball, a drawbar, the forward end ofwhich is formed to provide a seat for said ball, a block pivotallymounted on said drawbar and providing a seat for another portion of saidball, said block being lockable in a position wherein said ball may beuncoupled from said drawbar, and a locking lever adapted y to be rotatedto force said block against said ball, said lever being mounted on saiddrawbar at a point below a horizontalplane through the center of saidball, and having one end thereof in engagement with said block duringsaid rotation of the lever.

2. In a coupling for trailers, a ball, a drawbar forming a seat for oneside of said ball, a block pivotally mounted on said drawbar andproviding a seat for the other side of said ball, said block having afinger extending therefrom and formed integrally therewith, andalockinglever pivotally mounted on said drawbar and adapted upon rotationthereof in one direction to directly engage said block to force theblock against said ball, and upon rotation in the other direction todirectly engage and lift said nger to a position wherein the block iselevated and in a position to permit uncoupling of the ball from thedrawbar.

3. In a trailer coupling, a coupling element, a drawbar, a pressureblock plvotally mounted on said drawbar and normally engaging saidcoupling element to couple the latter with said drawbar, said blockbeing movable to a position in which said coupling element may beuncoupled from said drawbar, and toggle means for locking said block insaid position, said toggle means comprising a lever pivotally mounted onsaid drawbar and a nger projecting from and formed integrally `with saidblock, the lever directly engaging said finger, and spring meansinterposed between said drawbar and lever and acting to limit movementof said lever in an upward direction.

4. In a trailer coupling, a coupling element, a drawbar, a pressureblock pivotally mounted on said drawbar and normally engaging saidcoupling element to couple the latter with said drawbar, said blockbeing movable to a position in which said coupling element may beuncoupled from said drawbar, toggle means for locking` said block insaid position, and means operative in response to the coupling of saidelement with said drawbar for automatically releasing said block fromsaid position.

5. In a trailer coupling. a coupling element, a

vdrawbar, a pressure block pivotallymounted on li element.' p m CARL R.HEN'NICKE.

